Santi Cosma e Damiano was originally a Roman Catholic church affiliated with an Augustinian convent, it is now Greek Orthodox church.
Of the 12th-century Romanesque construction, only the bell-tower remains; the present facade and interiors mainly date to a reconstruction in the 18th century. The main altar (18th century) in polychrome marble has statues by Antonio Callegari and altarpiece by Giambettino Cignaroli and a 16th-century Ark of St Tiziano. Adjacent to the church is a 15th-century cloister. In 1923, at the instigation of a local poet Angelo Canossi, the names of the Italians who died in the war were inscribed in the columns.
References:The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.